Dielectric composition, dielectric film, and electronic component

ABSTRACT

A dielectric composition containing a crystalline phase represented by a general formula of Bi 12 SiO 20  and a crystalline phase represented by a general formula of Bi 2 SiO 5  as the main components. The dielectric composition contains preferably 5 mass % to 99 mass % of the Bi 2 SiO 5  crystalline phase, and more preferably 30 mass % to 99 mass %.

The present invention relates to a dielectric composition, a dielectricfilm and an electronic component.

BACKGROUND

Recently, with miniaturization and high performance of the devices suchas smart phone, notebook computer and the like, densification ofelectrical circuits is accelerating. Thus, low-back of electroniccomponents is in progress, and the requirement on the thin layer of thestructure becomes stricter and stricter.

Among them, examples using dielectric compositions include thin filmcapacitors, ceramic capacitors, and the like. They are widely applied inthe use of dielectric resonators or decoupling capacitors as electroniccomponents with a high performance, and thus, they are required to havea high relative permittivity, a small change of the electrostaticcapacity relative to temperature (hereinafter, it is recorded as thetemperature characteristic of electrostatic capacity), and a high Qvalue.

In addition, with densification of a circuit, it will turn to be a hightemperature due to the heat generated from an electronic component.Thus, it is required that the using environment temperature falls withina wide range of −55° C. to 125° C.

Up till now, the materials represented by a general formula of(Ba_(1-x)Sr_(x)) (Ti_(1-x)Zr_(x))O₃ are used as the material with goodtemperature characteristics of electrostatic capacity. However, thesematerials with bulk shape show a good temperature characteristic ofelectrostatic capacity, but when they are made into dielectric films,there is a problem that the relative permittivity will decrease due tothe size effect of the crystal particles. Thus, the requirement forminiaturization of such electronic components can not be met. Therefore,the development of the materials which have both a high relativepermittivity and a good temperature characteristic of electrostaticcapacity is progressing.

For example, in the Non-Patent Literature 1, it is disclosed that thetemperature characteristic of electrostatic capacity of Bi₁₂SiO₂₀ issmall. However, although Bi₁₂SiO₂₀ shows a good temperaturecharacteristic of electrostatic capacity, its relative permittivity isas low as 38.

NON-PATENT LITERATURE

-   Non-Patent Literature 1: Journal American Ceramic Society Vol. 84    No. 12 P2900˜2904, Processing and Dielectric Properties of Sillenite    Compounds Bi₁₂MO_(20-σ) (M=Si, Ge, Ti, Pb, Mn, B_(1/2), P_(1/2)),    Matjaz Valent, Danilo Suvorov.

SUMMARY

The present invention is accomplished in view of such actual situation.The purpose of the present invention is to provide a dielectriccomposition and a dielectric film which maintain a high relativepermittivity and show a good temperature characteristic of electrostaticcapacity. Also the present invention aims at providing an electroniccomponent with a high electrostatic capacity and a good temperaturecharacteristic of electrostatic capacity by having electrodes anddielectric layer(s) containing dielectric composition mentioned above.

In order to achieve the above aim, the dielectric composition accordingto the present invention characterized in that it contains a crystallinephase represented by a general formula of Bi₁₂SiO₂₀ and a crystallinephase represented by a general formula of Bi₂SiO₅ as the maincomponents.

The content of the crystalline phase of Bi₂SiO₅ is preferably 5 mass %to 99 mass %, and more preferably 30 mass % to 99 mass %.

In addition, the dielectric film preferably contains the abovedielectric composition as the main component.

In the electronic component containing dielectric layer(s) andelectrodes, it preferably contains the above dielectric composition asthe main component of the dielectric layer.

The present invention can provide a dielectric composition and adielectric film which maintain a high relative permittivity and show agood temperature characteristic of electrostatic capacity. Also, thepresent invention can provide an electronic component with a highelectrostatic capacity and a good temperature characteristic ofelectrostatic capacity by having electrodes and dielectric layer(s)containing the dielectric composition mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section view of the thin film capacitor according toan embodiment of the present invention.

FIG. 2 is a cross-section view of the single plate capacitor accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention is described withreference to the figures.

As for the embodiment of the present invention, the shape is notparticularly limited. In the dielectric film, the effect of thedielectric composition is evaluated with the thin film capacitor havingthe shape shown as follows.

<Thin Film Capacitor 10>

As shown in FIG. 1, a thin film capacitor 10 according to the presentembodiment has a lower electrode structure 3, an upper electrodestructure 5 and a dielectric film 4 on a foundation layer 2 which isprepared on the surface of a supporting substrate 1. And, the dielectricfilm 4 is disposed between the lower electrode structure 3 and the upperelectrode structure 5. The supporting substrate 1 has a function toensure the mechanical strength of the whole thin film capacitor 10. Thefoundation layer 2 plays a role in bonding the supporting substrate, aelectrode film of the lower electrode structure 3 and the dielectricfilm 4.

<Supporting Substrate 1>

The material for forming the supporting substrate 1 as shown in FIG. 1is not particularly limited. The supporting substrate 1 can be formedwith a single crystal such as Si single crystal, SiGe single crystal,GaAs single crystal, InP single crystal, SrTiO₃ single crystal, MgOsingle crystal, LaAlO₃ single crystal, ZrO₂ single crystal, MgAl₂O₄single crystal, NdGaO₃ single crystal, or a ceramic polycrystallinesubstrate such as Al₂O₃ polycrystal, ZnO polycrystal, SiO₂ polycrystal,or a metal substrate and so on. Among them, Si single crystal is themost preferable due to the low cost. The surface of the supportingsubstrate 1 needs to carry out an insulating treatment to make thecurrent not flow into the supporting substrate 1 in use. For example, aninsulating layer can be formed by oxidizing the surface of thesupporting substrate 1 or a film can be formed on the surface of thesupporting substrate 1 with an insulator such as Al₂O₃, SiO₂, Si₃N₄ andthe like. The thickness of the supporting substrate 1 is notparticularly limited as long as it can ensure the mechanical strength ofthe whole thin film capacitor. For example, it can be set to be 10 nm to1000 nm.

<Foundation Layer 2>

In the present invention, the thin film capacitor 10 shown in FIG. 1preferably have a foundation layer 2 on the surface of the supportingsubstrate 1 dealt with the insulating treatment. The foundation layer 2plays a role in bonding the electrode film which is used as the lowerelectrode structure 3 to the supporting substrate 1, and bonding thedielectric film 4 to the electrode film which is used as the lowerelectrode structure 3. If the foundation layer 2 is annealed, oxide isformed in a part of the foundation layer 2 and it precipitates on theelectrode film of the lower electrode structure 3. Thus, the dielectricfilm 4 and the electrode film that is used as the lower electrodestructure 3 can be bonded. The material for forming the foundation layer2 is not particularly limited as long as it can bond the electrode filmwhich is used as the lower electrode structure 3 to the supportingsubstrate 1, and bond the dielectric film 4 to the electrode film whichis used as the lower electrode structure 3. For example, the foundationlayer 2 can be formed with the oxide of titanium or chromium, and thelike.

If no peeling occurs between the supporting substrate 1 and theelectrode film which is the lower electrode structure 3 and between thedielectric film 4 and the electrode film which is the lower electrodestructure 3, a foundation layer 2 may not be added between thesupporting substrate 1 and the lower electrode structure 3, and betweenthe lower electrode structure 3 and the dielectric film 4.

<Lower Electrode Structure 3>

The material for forming the lower electrode structure 3 is notparticularly limited as long as it is conductive. It can be formed witha metal such as platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium(Pd), iridium (Ir), gold (Au), silver (Ag), copper (Cu), nickel (Ni) andthe like, and etc. Among these materials, in the case of being used inthe high-frequency electronic components, Cu is the most preferablematerial. In the present invention, Bi (bismuth) with a low meltingpoint is used, and thus the material can be fired under a lowtemperature that is 150° C. or more lower than the(Ba_(1-x)Sr_(x))(Ti_(1-x)Zr_(x))O₃-based material which is used as thematerial with a fine temperature characteristic of electrostaticcapacity nowadays. Therefore, Cu with a low melting point can be used asthe electrode material. The thickness of the lower electrode structure 3is not particularly limited as long as it can function as one electrodeof the thin film capacitor. For example, it can be set to be 10 nm to10000 nm.

After the lower electrode structure 3 being formed, annealing is carriedout to strengthen the bonding of the supporting substrate 1, thefoundation layer 2 and the lower electrode structure 3. The heating ratein the annealing process is preferably 50° C./hr to 8000° C./hr, andmore preferably 100° C./hr to 8000° C./hr. The holding temperature inthe annealing process is preferably 400° C. to 800° C., and morepreferably 400° C. to 700° C. Its holding time is preferably 0.1 hour to4 hours, and more preferably 0.2 hour to 3 hours, and particularlypreferably 0.5 hour to 2 hours.

<Dielectric Film 4>

The dielectric film 4 is composed of the dielectric compositionaccording to the present embodiment. The dielectric composition is adielectric composition containing a crystalline phase represented by ageneral formula of Bi₁₂SiO₂₀ and a crystalline phase represented by ageneral formula of Bi₂SiO₅ as the main components. The main componentsmentioned here refer to the compounds contained 50 mass % or more in thedielectric film.

The cubic Bi₁₂SiO₂₀ that is a paraelectric material will lead to crystallattice distortion in the interface between Bi₁₂SiO₂₀ and Bi₂SiO₅ bycontaining orthorhombic Bi₂SiO₅. It is considered that ionicpolarizability is enhanced by this crystal lattice distortion, and thusits relative permittivity become higher than that of the single phase ofthe Bi₁₂SiO₂₀ crystal layer. It is believed that because the effect ofincreasing the ionic polarization is high, the system can achieve anunprecedented high relative permittivity by only 5 mass % or more ofBi₂SiO₅ contained in the paraelectric material of Bi₁₂SiO₂₀.

In addition, it is predicted that the Curie point of Bi₂SiO₅ falls intoa high temperature higher than 150° C. The relative permittivity willbecome high with the increase of the temperature, and the temperaturecharacteristic of electrostatic capacity will deteriorate and becomelarge. On the other hand, the relative permittivity of the paraelectricmaterial of Bi₁₂SiO₂₀ changes little relative to temperature. Thus, itis presumed that crystal lattice distortion will occur in theorthorhombic Bi₂SiO₅ by containing cubic Bi₁₂SiO₂₀, and thus the Curiepoint will shift to a higher temperature. Therefore, the increase of therelative permittivity could be inhibited in the temperature range of−55° C. to 125° C., and a good temperature characteristic ofelectrostatic capacity could be achieved.

Besides, in the present invention, Bi₂SiO₅ has a layer structure withBi₂O₃ layers and SiO₂ layers laminated alternately. Thus, even if only 1mass % of Bi₁₂SiO₂₀ is contained, the ordinality in a part of it willbreak up, and thus an effect of shifting the Curie point to a highertemperature will be produced and a good temperature characteristic ofelectrostatic capacity can be obtained. Because of this effect, a goodtemperature characteristic of electrostatic capacity is shown with ahigher value than the assumed one obtained by simply adding thetemperature characteristic value of electrostatic capacity of Bi₂SiO₅ tothat of Bi₁₂SiO₂₀.

The content of the crystalline phase of Bi₂SiO₅ in the dielectriccomposition is preferably 5 mass % to 99 mass %, and more preferably 30mass % to 99 mass %. By being such range, a good temperaturecharacteristic of electrostatic capacity can be maintained and therelative permittivity can be increased. As the temperaturecharacteristic of electrostatic capacity of the dielectric compositionis 1000 ppm/° C. or less, it can meet the COM standards of the EIAspecification. The dielectric composition contains a Bi₂O₃ crystal phaseor a SiO₂ amorphous phase as the tertiary phase in a nonequilibriumstate of reaction, and these phases will not deteriorate the dielectricproperties largely.

The dielectric film according to the present embodiment can furthercontain other components such as transition elements or rare earthelements and etc. according to the desired properties.

The thickness of the dielectric film 4 is preferably 50 nm to 2000 nm,and more preferably 100 nm to 2000 nm, and further more preferably 200nm to 2000 nm. If it is 50 nm or less, dielectric breakdown will occurseasily. In the case of 2000 nm or more, the obtained electrostaticcapacity will be reduced, and thus it is not preferred. Additionally,the material will become dense by being made into a dielectric film, anda high relative permittivity can be obtained.

The dielectric film 4 can be formed with all kinds of deposition methodsuch as vacuum deposition method, sputtering method, pulsed laserdeposition method (PLD method), metal-organic chemical vapor depositionmethod (MOCVD), metal organic decomposition method (MOD) or chemicalsolution deposition methods like sol-gel method and the like, or etc.

After the forming of the dielectric film 4, annealing is carried out.The heating rate in the annealing process is preferably 50° C./hr to8000° C./hr, and more preferably 200° C./hr to 8000° C./hr. The holdingtemperature in the annealing process is preferably 650° C. or less, andmore preferably 450° C. to 650° C. The holding time is preferably 0.1hour to 4 hours, more preferably 0.2 hour to 3 hours, and particularlypreferably 0.2 hour to 2 hours. By making the holding temperature andthe holding time fall within such ranges, the volatilization of Bi canbe inhibited, a metastable phase of Bi₂SiO₅ crystal phase can begenerated, and a dielectric composition containing a crystalline phaserepresented by a general formula of Bi₁₂SiO₂₀ and a crystalline phaserepresented by a general formula of Bi₂SiO₅ as the main components canbe obtained.

<Upper Electrode Structure 5>

In the present invention, the thin film capacitor has an upper electrodestructure 5 on the surface of the dielectric film 4 which functions asthe other electrode of the thin film capacitor. The material for formingthe upper electrode structure 5 is not particularly limited as long asit is conductive. The upper electrode structure 5 can be formed by thesame material as that of the lower electrode structure 3. Further, asthe electrode film used as the upper electrode structure 5 can be formedunder a room temperature, base metals such as iron (Fe), nickel (Ni) andetc. or alloy such as tungsten silicide (WSi), molybdenum silicide(MoSi) and etc. can be used to form the film of the upper electrodestructure. The thickness of the upper electrode structure 5 is notparticularly limited as long as it can function as the other electrodeof the thin film capacitor. For example, it can be set to be 10 nm to10000 nm.

In the embodiment mentioned above, thin film capacitor is illustrated asthe electronic component according to the present invention. However,the electronic component according to the present invention is notlimited to the thin film capacitor, and it can be any electroniccomponent containing the above dielectric composition.

Moreover, a single plate capacitor also can be obtained in the presentinvention. The single plate capacitor has a dielectric layer disposedbetween electrode layers as shown in FIG. 2. The dielectric layercontains a crystalline phase represented by a general formula ofBi₁₂SiO₂₀ and a crystalline phase represented by a general formula ofBi₂SiO₅ as the main components.

<Single Plate Capacitor 20>

As shown in FIG. 2, the single plate capacitor 20 according to thepresent embodiment has electrode layers 7 and a dielectric layer 6 whichis disposed between the two electrode layers 7.

The shape of the single plate capacitor 20 is not particularly limitedand the size also is not particularly limited. It can be a size suitablefor using and for example it can be set as 10 mm×10 mm×1 mm and thelike.

<Dielectric Layer 6>

The dielectric layer 6 is composed of the dielectric compositionaccording to the present embodiment. The dielectric composition containsa crystalline phase represented by a general formula of Bi₁₂SiO₂₀ and acrystalline phase represented by a general formula of Bi₂SiO₅ as themain components. The content of Bi₂SiO₅ crystalline phase is preferably5 mass % to 99 mass %, and more preferably 30 mass % to 99 mass %. Thus,a high relative permittivity can be maintained and a good temperaturecharacteristic of electrostatic capacity can be realized.

The thickness of the dielectric layer 6 is not particularly limited. Itcan be properly decided according to the desired properties and the useand etc. For example, it can be set to be 0.1 mm to 3 mm.

<Electrode Layer 7>

The conductive material contained in the electrode layer 7 is notparticularly limited as long as it is conductive. It can be properlyselected from conductive materials such as metals like platinum (Pt),indium-gallium (In—Ga), palladium (Pd), gold (Au), silver (Ag), copper(Cu), and the like. The thickness of the electrode layer 7 is notparticularly limited as long as it can function as an electrode.

<Method for Manufacturing Single Plate Capacitor>

The single plate capacitor of the present embodiment is manufactured bysandwiching a dielectric layer between two electrode layers. And thedielectric layer contains a crystalline phase represented by a generalformula of Bi₁₂SiO₂₀ and a crystalline phase represented by a generalformula of Bi₂SiO₅ as the main components. Hereinafter, themanufacturing method is described specifically.

Firstly, a specified amount of Bi₂O₃ powders and SiO₂ powders areprepared as the dielectric material for forming the dielectric layer 6.And then they are mixed as well as a solvent by a ball mill.

The solvent used for mixing can be organic solvent, and also can bewater.

The organic solvent is not particularly limited, and can be properlyselected from various organic solvents such as ethanol, acetone, tolueneand the like.

After mixing, the mixed solution is dried. The drying method is notparticularly limited, and can be properly selected. In the case ofdrying with a thermostat, the drying temperature is not particularlylimited as long as the solvent can evaporate. In the case offreeze-drying, the freezing temperature is preferably 30° C. lower thanthe freezing point of the mixed solution, and more preferably 40° C. to50° C. lower than the freezing point of the mixed solution.

The dried mixture powders are added into a platinum crucible to bemelted. The holding temperature during melting is preferably 900° C. orhigher, and more preferably 1000° C. to 1050° C. The holding time ispreferably 1 hour or more, and more preferably 2 hours to 5 hours. Thevolatilization of Bi can be inhibited by making the holding temperatureand the holding time fall within such ranges, and then a specifiedcomposition can be obtained.

The melted material is then quenched in cold water until 100° C. or lessto obtain an intermediate.

The obtained intermediate is cut and then polished to obtain a singleplate sample. The size is not particularly limited. For example, it canbe set to be 10 mm×10 mm×1 mm and the like. It also can be properlydetermined according to the desired properties or use and etc.

The single plate sample is then annealed. The holding temperature in theannealing process is preferably 830° C. or less, more preferably 400° C.to 700° C., and particularly preferably 400° C. to 550° C. The holdingtime is preferably 1 day or more, more preferably 3 days to 7 days, andparticularly preferably 5 days to 7 days. Then, a dielectric layer isobtained. By making the holding temperature and the holding time fallinto such ranges, a metastable phase of Bi₂SiO₅ crystal phase can begenerated, and a dielectric composition containing a Bi₁₂SiO₂₀crystalline phase and a Bi₂SiO₅ crystalline phase can be obtained.

As shown in FIG. 2, electrodes are coated on the dielectric layer toform a single plate capacitor. The conductive material contained in theelectrodes is not particularly limited as long as it is conductive. Itcan be properly selected from conductive materials such as metals likeplatinum (Pt), indium-gallium (In—Ga), palladium (Pd), gold (Au), silver(Ag), copper (Cu) and the like.

Hereinbefore, embodiments of the present invention are described, butthe invention is not restricted by the embodiments mentioned above. Itcan make various changes without deviating from the scope of the presentinvention.

EXAMPLES

Hereinafter, the present invention is specifically described based onthe examples. However, the present invention is not restricted by theexamples.

Examples 1 to 7

Examples 1 to 7 were thin film capacitors obtained by forming dielectricfilms using a sputtering method. Firstly, a foundation layer of Ti filmwith a thickness of 50 nm was formed by a sputtering method on thesurface of a substrate with a square of 10 mm×10 mm, and the substratehad SiO₂ on the surface of Si.

Next, a Pt film used as the lower electrode structure was formed on theobtained Ti film by a sputtering method and the thickness of the Pt filmwas made be 50 nm.

Then, the formed Pt/Ti film was annealed under a condition with aheating rate of 200° C./hr, a holding temperature of 650° C., a holdingtime of 0.5 hr and an atmosphere of air.

The target for sputtering was prepared by a solid-phase method, and thetarget was used to form the dielectric film containing a crystallinephase represented by Bi₁₂SiO₂₀ and a crystalline phase represented byBi₂SiO₅ as the main components.

The component ratio of the Bi₁₂SiO₂₀ crystalline phase and the Bi₂SiO₅crystalline phase could be adjusted by the mass ratio of the startingmaterials of Bi₂O₃ and SiO₂.

Firstly, the target was essential for forming the dielectric filmcontaining a crystalline phase represented by Bi₁₂SiO₂₀ and acrystalline phase represented by Bi₂SiO₅ as the main components. As forthe starting materials of the target for sputtering, Bi₂O₃ powders andSiO₂ powders were prepared respectively and the mass ratio of the targetmaterials of Bi₂O₃ and SiO₂ in Examples 1 to 7 was adjusted as shown inTable 1.

Subsequently, water was used as the solvent, and the powders werewet-mixed for 20 hours. Then the mixed powders were dried under 100° C.

The obtained mixed powders were pressed to obtain a molded body. Thecondition for molding was that the pressure was 2.0×10⁸ Pa, and thetemperature was 25° C.

Then, the molded body was sintered in a condition with a holdingtemperature of 850° C., a holding time of 2 hours and an atmosphere ofair.

Next, the obtained sintered body was processed into a shape of 200 mmφand a thickness of 6 mm by a flat-surface grinding machine and acylindrical sanding machine, and a target for sputtering was obtained.The target was essential for forming the dielectric film containing acrystalline phase represented by Bi₁₂SiO₂₀ and a crystalline phaserepresented by Bi₂SiO₅ as the main components.

In order to form a dielectric film (the dielectric film contained acrystalline phase represented by Bi₁₂SiO₂₀ and a crystalline phaserepresented by Bi₂SiO₅ as the main components) on the annealed lowerelectrode structure film, deposition was conducted with the above targetby a sputtering method under a condition with the atmosphere being argon(Ar)/oxygen (O₂)=2/1, the pressure being 1.2 Pa, a high-frequency powerbeing 200 W and the substrate temperature being room temperature. Afterthat, annealing was carried out under the following condition to obtaina dielectric film. The thickness of the dielectric film was 400 nm.

The condition for annealing was that the heating rate was 600° C./hr,the holding temperature was 490° C., the holding time was 2 hours, andthe atmosphere was air.

Next, a Pt film used as the upper electrode structure with a diameter of5 mm and a thickness of 50 nm was formed on the obtained dielectric filmby a sputtering method using a mask, and thus the thin film capacitorsamples of Examples 1 to 7 shown in FIG. 1 were obtained.

The relative permittivity, the temperature characteristic ofelectrostatic capacity, and the mass ratio of Bi₁₂SiO₂₀ crystallinephase and Bi₂SiO₅ crystalline phase of the obtained thin film capacitorwere measured with the following methods respectively.

<Relative Permittivity ∈_(r)>

The relative permittivity ∈_(r) was calculated from the electrostaticcapacity C of the dielectric sample. The electrostatic capacity C wasmeasured by a digital LCR meter (4274A manufactured by YHP Corporation)under a reference temperature of 25° C. in the condition of thefrequency being 1 MHz and the input signal level (measuring voltage)being 1.0 Vrms. The relative permittivity is the higher the better. Inthe present examples, it was preferably 40 or more, more preferably 50or more, and particularly preferably 60 or more. The results were shownin Table 1.

<Temperature Characteristic of Electrostatic Capacity TCC>

The electrostatic capacity of the dielectric sample was measured under−55° C. to 125° C. in a condition of the frequency being 1 MHz and theinput signal level (measuring voltage) being 1.0 Vrms. When thereference temperature was set to be 25° C., the temperature coefficientrelative to temperature was preferred to be 1000 ppm/° C. or less, andmore preferred to be 700 ppm/° C. or less. The coefficient oftemperature characteristic TCC (ppm/° C.) was calculated with thefollowing mathematical formula 1. In the mathematical formula 1, theC₁₂₅ represented electrostatic capacity under 125° C. and the C₂₅represented electrostatic capacity under 25° C.TCC(1 MHz)={(C ₁₂₅ −C ₂₅)/C ₂₅}×100<Measurement of the Mass Ratio of Bi₁₂SiO₂₀ and Bi₂SiO₅>

Firstly, the X-ray diffraction of the film sample was performed by aparallel beam method and the single plate sample was measured by afocusing method. Cu—Kα X-ray was used as an X-ray source. The measuringcondition was the voltage of 45 kV and the range of 2θ=20° to 70°. Themass ratio of the crystalline phases was calculated by a quantitativeanalysis method, i.e., a matrix flushing method, using the obtainedresults of X-ray diffraction and reference intensity ratio of Bi₁₂SiO₂₀and Bi₂SiO₅ obtained from PDF databases. The analysis of the measureddata was carried out by using the analysis software of H′Pert High ScorePlus. As for the reference code of the PDF database, 01-072-7675 wasused for Bi₁₂SiO₂₀ and 01-075-1483 was used for Bi₂SiO₅. In order to geta result of the mass ratio with a higher accuracy, measuring number was3 for one sample and the average value was calculated thereby.

The measured results were shown in Table 1.

TABLE 1 Mass ratio of Mass fraction Mass fraction Relative TCC Shape ofsample the materials, of Bi₁₂SiO₂₀ of Bi₂SiO₅ permittivity 1 MHz SampleNo. (deposition method) i.e., Bi₂O₃/SiO₂ (%) (%) 1 MHz (ppm/° C.)Example 1 Thin film (sputtering 46.1 99.0 1.0 42 132 method) Example 2Thin film (sputtering 45.0 96.1 3.9 45 315 method) Example 3 Thin film(sputtering 44.5 94.8 5.2 51 373 method) Example 4 Thin film (sputtering34.9 69.9 30.1 64 566 method) Example 5 Thin film (sputtering 28.9 54.545.5 75 621 method) Example 6 Thin film (sputtering 12.9 13.2 86.8 93619 method) Example 7 Thin film (sputtering 8.1 0.8 99.2 97 753 method)Example 8 Thin film (PLD 34.9 70.7 29.3 73 579 method) Example 9 Singleplate 34.9 70.3 29.7 59 548 Example 10 Single plate 28.9 54.1 45.9 68584 Example 11 Single plate 12.9 13.0 87.0 87 599 Comparative Thin film(sputtering 46.5 100.0 0.0 38 145 Example 1 method) Comparative Thinfilm (sputtering 7.8 0.0 100.0 102 1151 Example 2 method)

Example 8

Example 8 was a thin film capacitor prepared by forming a dielectricfilm using a PLD method. Firstly, Bi₂O₃ powders and SiO₂ powders wereprepared respectively with the mass ratio of Bi₂O₃ and SiO₂ as thematerials of the target of Example 8 as shown in Table 1. And a targetfor PLD was produced by using the same target preparing method as thatin Example 1.

Next, a dielectric film composed of a crystalline phase represented byBi₁₂SiO₂₀ and a crystalline phase represented by Bi₂SiO₅ was formed by aPLD method, and then the dielectric film with a thickness of 400 nm wasformed by using the target for PLD on the obtained lower electrodestructure with the same method as that in Example 1. The thin filmcapacitor of Example 8 was prepared with the same method as that ofExample 1 except that the dielectric film was formed by a PLD method.

The obtained thin film capacitor of Example 8 was evaluated with thesame method as that of Example 1. The results were shown in Table 1.

Examples 9 to 11

Examples 9 to 11 were examples of single plate capacitor.

Firstly, as for the starting materials of the dielectric layers ofExamples 9 to 11, Bi₂O₃ powders and SiO₂ powders were preparedrespectively with the mass ratio of Bi₂O₃ and SiO₂ being the same asshown in Table 1.

Subsequently, the materials and water were mixed with a ball mill, andthe obtained mixture was dried under 100° C.

The mixed powders were melted in a condition with a holding temperatureof 1000° C., a holding time of 1 hour and an atmosphere of air, and thenquenched with cold water to prepare an intermediate.

The obtained intermediate was cut and polished to be a size of 10 mm×10mm with a height of 1 mm. Then, it was annealed in a condition with aholding temperature being 400° C., a holding time being 5 days and anatmosphere of air. A dielectric layer containing a crystalline phaserepresented by Bi₁₂SiO₂₀ and a crystalline phase represented by Bi₂SiO₅as the main components was obtained.

As shown in FIG. 2, Ag electrode was coated on the obtained dielectriclayer to obtain the single plate capacitor samples of Examples 9 to 11.

The single plate capacitor samples of Examples 9 to 11 obtained therebywere evaluated with the same method as that of Example 1. The resultswere shown in Table 1.

Comparative Example 1

Firstly, Bi₂O₃ powders and SiO₂ powders were prepared respectively withthe mass ratio of Bi₂O₃ and SiO₂ of the starting material for theBi₁₂SiO₂₀ target shown in Table 1. And a Bi₁₂SiO₂₀ target for sputteringwas prepared by using the same method as that of Example 1.

The thin film capacitor sample of Comparative Example 1 was preparedwith the same method as that of Example 1 except the mass ratio of thetarget for sputtering.

The thin film capacitor sample of Comparative Example 1 obtained therebywas evaluated with the same method as that of Example 1. The resultswere shown in Table 1.

Comparative Example 2

Firstly, Bi₂O₃ powders and SiO₂ powders were prepared respectively withthe mass ratio of Bi₂O₃ and SiO₂ of the starting material for theBi₂SiO₅ target shown in Table 1. And a Bi₂SiO₅ target for sputtering wasprepared by using the same method as that of Example 1.

A thin film capacitor sample of Comparative Example 2 was prepared withthe same method as that of Example 1 except the mass ratio of the targetfor sputtering.

The thin film capacitor sample of Comparative Example 2 obtained therebywas evaluated with the same method as that of Example 1. The resultswere shown in Table 1.

Examples 1 to 8

It could be confirmed from Table 1 that in the cases of the dielectriccomposition in which the main component contains a crystalline phaserepresented by Bi₁₂SiO₂₀ and a crystalline phase represented by Bi₂SiO₅,a high relative permittivity could be maintained and a good temperaturecharacteristic of electrostatic capacity could be realized regardless ofthe deposition method.

Examples 9 to 11

It could be confirmed from Table 1 that in the cases of the dielectriccomposition containing a crystalline phase represented by Bi₁₂SiO₂₀ anda crystalline phase represented by Bi₂SiO₅, a high relative permittivitycould be maintained and a good temperature characteristic ofelectrostatic capacity could be achieved even though the dielectriccomposition was made into a shape of single plate.

Examples 1 to 11

It could be known from Table 1 that as for the dielectric compositioncontaining a crystalline phase represented by Bi₁₂SiO₂₀ and acrystalline phase represented by Bi₂SiO₅, the relative permittivity witha thin film shape was higher than that with a single plate shape.

Comparative Example 1 and Comparative Example 2

It could be seen from Table 1 that in the case that the dielectriccomposition was not the one containing a crystalline phase representedby Bi₁₂SiO₂₀ and a crystalline phase represented by Bi₂SiO₅, therelative permittivity and the temperature characteristic ofelectrostatic capacity could not be improved at the same time.

As described above, the present invention relates to a dielectriccomposition, a dielectric film and an electronic component. The presentinvention can provide a dielectric composition and a dielectric filmwhich can maintain a high relative permittivity and show a goodtemperature characteristic of electrostatic capacity. Miniaturizationand high performance of the electronic components using the dielectriccomposition can be realized. The present invention provides a widespreadnew technology for such as the thin film capacitor or the filmhigh-frequency components or the like using a dielectric film.

DESCRIPTION OF REFERENCE NUMERALS

1: supporting substrate; 2: foundation layer; 3: lower electrodestructure; 4: dielectric film; 5: upper electrode structure; 10: thinfilm capacitor; 6: dielectric layer; 7: electrode layer; 20: singleplate capacitor

What is claimed is:
 1. A capacitor comprising: a first electrode; asecond electrode; and a dielectric film disposed between the firstelectrode and the second electrode, wherein the dielectric film iscomposed of a dielectric composition comprising a crystalline phaserepresented by a general formula of Bi₁₂SiO₂₀ and a crystalline phaserepresented by a general formula of Bi₂SiO₅ as the main components. 2.The capacitor according to claim 1, wherein the content of saidcrystalline phase represented by Bi₂SiO₅ is 5 mass % to 99 mass %. 3.The capacitor according to claim 1, wherein the content of saidcrystalline phase represented by Bi₂SiO₅ is 30 mass % to 99 mass %. 4.The capacitor according to claim 1, wherein a thickness of thedielectric film is in the range of from 50 nm to 2000 nm.
 5. Thecapacitor according to claim 1, wherein a thickness of the dielectricfilm is in the range of from 200 nm to 2000 nm.
 6. A capacitorcomprising: a first electrode; a second electrode; and a dielectriclayer disposed between the first electrode and the second electrode,wherein the dielectric layer is composed of a dielectric compositioncomprising a crystalline phase represented by a general formula ofBi₁₂SiO₂₀ and a crystalline phase represented by a general formula ofBi₂SiO₅ as the main components; wherein a thickness of the dielectriclayer is in the range of from 0.1 mm to 3 mm.